of chicago



May 26, 1931. R. w. ARMS PROCESS OF CLEANING COAL Original. Filed May 23, 1927 253a WUZTWQS Z2 RAY W. ARMS, OF CHICAGO, ILLINOIS,

' deck. 13

able fabric extending I hood to the deck. This bellows Patented May 26,. 1931 UNITED STATES PATENT OFFICE ASSIGNOR ,TO ROBERTS AND SCHAE'FEB- COM- FANY, OF CHICAGO, ILLINOIS, A CORPORATION 01 ILLINOIS rnoonss or CLEANING coax.

Original application filed May 2a, 1927,

My invention relates to dust collecting systems for air separating tables and the like and to a process of handling dust laden air therefrom. It has for one object to provide a new and improved apparatus and process whereby dust generated air set free by an air separating table may be separated from the air returned to the system and whereby the volume of air which has to be separately'treated for dust separation will be reduced. Other objects will a pear from time to time throughout the specification and claims. This application is a division of my co'pending application Serial Number 193,468 filed May 23, 1927. My invention is illustrated more or less diagrammatically in the accompanying drawings, wherein-- Figure l is a side elevation of an apparatus embodying my invention;

Figure 2 is an end elevation.

Like parts are indicated by like characters throughout the specification and drawings.

A is an air pervious material separating deck. It is reciprocated by a pulley A driving a crank A and a link A shelf reciprocating with the deck adapted to receive coal or other material to he treated which is discharged thereupon through a spout A from a hopper A. A A A are material discharge chutes which collect and discharge the separated material from the table or deck.

B is a blower driven by a motor B and discharging air under pressure through the chimney B to the underside of the pervious is a dust hood located above the deck. B is a bellows of flexible or other suit- Y down from the lower edge of the extending down to the deck throughout -the major portion of its periphery only so much ofthe space between the hood and the deck being open as is necessary to perm1t the at tendant to inspect theoperation of the machine. B is a funnel forming partof the hood B discharging into a pipe 13 which pipe leads to any suitable dust collecting and separating apparatus. This funnel is located over the feed corner of the table or deck, that supply leading A is a feed Serial No. 193,468. Divided and this application filed March 10, 1928. Serial No. 26@,565.

is-,that part of the deck or table where the major portion of the dust originates. The dust separator-since its detailsform no part of the invention is only shown diagrammatically as at B".

Extending from the dust hood B in an air recirculation pipe C. It discharges into a dust trap C and a pipe C leads therefrom to the intake side of the fan B. C is a conveyor adapted to carry ofl the dust brought down from the air by the dilst trap or settling chamber C is an adjusting make up air to the intake of the fan. The necessity of this is caused by the fact that carried ofl it comes back to the fan or blower. Some of B and the deck and the, adjustable make up opening will be so set) and controlledeither manually or automatically that there will always be an inflow of air between the hood and the deck and never an outflow.

The result of this is that no dust laden air gets out into the room or house in which the table is operating. The tendency of air flow is always inward'in the entire system except that part of it leading from the blower to the underside of the deck which alone is not under sub-atmospheric pressure. Thus there is no tendency for dust to escape anywhere from the system into the-room.

Except in connection withthe very finest screens the presence of dust in therecnculated air and therefore in the air blown up throughthe screen or pervious deck to float and assist in separating the material, is not a detriment but an advantage because it is understood that in connection with dust separating the flowing stream of finely divided material travels along a separating table under the influence of gravity, the reciprocation of the table and the floating effect of the and traveling up through it and through the the make up air comes in between the hood bed of material increasing to some extent as it does the specific gravity of the air, helps rather than hinders in the separating operation.

Experience shows that there is a saturation point at which the air stream will carry no further dust. Beyond that point dust may be deposited out in the dust trap or may be screened out by the bed of traveling material to be treated.

Only that relatively small proportion of the air having the maximum amount of dust is' drawn out through the funnel and discharged to a separate dust collector. Thus a relatively small dust collector can be used and a high degree of efliciency in dust collection can be obtained. It is ordinarily not desirable to attempt to recirculate all the air because unless the space between the hood and the deck is made air tight there will be a leakage inward about the edges of the deck and this constant increase in the amount of air drawn away from the deck over that fed to it must be compensated for by bleeding off some of the air and recirculating the balance. Moreover a never ending recirculation might result in so saturating the recirculated air with dust and dirt particles that the screening system might become clogged.

While I have shown part of the air taken from the hood and discharged through a dust separator, it is obvious that such air may be discharged into any suitable system and the dust separator needs not to be of any particular type and might take any number of different forms and in fact it is conceivable that many things might be done to the air before it reaches the dust separator or it might merely be discharged away from the system.

One of the important reasons for taking some of the air from the hood and discharging it either to a separator or hood is that by doingthis it becomes possible to keep all the air except that portion below the deck under sub-atmospheric pressure so that all leaks will be in, instead of out, and there will be no tendency for dust laden air to escape from the system into the room or house where the system is located.

While I have shown my device as applied to the cleaning of coal and have so described and claim it, it is obvious that coal is merely one of the materials which might be cleaned, it happening to be that coal is the material which applicant is now cleaning. Quite obyiously, however, other materials which would generate dust could be cleaned by the same method and I wish it understood that where I refer to a coal cleaning system, I am using the term coal merely for the purpose of illustration.

I claim 1. The process of cleaning coal by air which consists in forcing 2. hi h pressure stream of air through a fiowingied of coal,

said stream including a portion of the dust laden air from above the bed togetherwith an additional supply of air, withdrawing the resultant air from above the bed, recirculating part of it through the coal bed and withdrawing the remainder from the system.

2, The process of cleaning coal by air which consists in forcing a high pressure stream of air through a flowing bed of coal, said stream including a portion of the dust laden air from above the bed together with an additional supply of air, withdrawing the resultant air from above-the bed, recirculating part of it through the coal bed and withdrawing the remainder-from the system, the quantity of air withdrawn from the system being substantially equal to the additional quantity of air added to the system above the bed.

3. The process of treating dust-laden air from air cleaning systems wherein cleaning takes place in a stratifying zone in accordance with specific gravity, which consists in withdrawing a part of the spent dust-laden air, from the system above the zone and in re-circulating the balance of the dust-laden air through the zone. l

4. The process of treating dust-laden air from air cleaning systems wherein cleaning takes place in a stratifying zone in accordance with specific gravity, which consists in withdrawing a part of the spent dust-laden air, from the system above the zone, and in recirculating the balance of the dust-laden air through the zone while maintaining all parts of the s stem except that part which conducts the wor (ing air under pressure to the stratifying zone, under sub-atmospheric pressure.

Signed at Chicago, county of Cook and State of Illinois, this 6th day of March, 1928.

RAY W. ARMS. 

